| 时间 | 值 （亿美元） | 世界排名 |
|---|---|---|
| 2016 | 15.3 | 42 |
| 2015 | -1.4 | 190 |
| 2014 | 33 | 56 |
| 2013 | -.7 | 184 |
| 2012 | 40 | 52 |
| 2011 | 13.8 | 83 |
| 2010 | 2.9 | 126 |
| 2009 | -.5 | 187 |
| 2008 | 25.9 | 68 |
| 2007 | 43.4 | 61 |
| 2006 | 29.1 | 62 |
| 2005 | 19.1 | 62 |
| 2004 | 23.2 | 44 |
| 2003 | -33.6 | 193 |
| 2002 | 28.5 | 34 |
| 2001 | 2.6 | 84 |
| 2000 | -15.1 | 184 |
| 1999 | 11.5 | 46 |
| 1998 | 12.8 | 43 |
| 1997 | 24.7 | 36 |
| 1996 | 23.4 | 30 |
| 1995 | 33.2 | 22 |
| 1994 | 25 | 21 |
| 1993 | 24 | 15 |
| 1992 | 19.3 | 17 |
| 1991 | 12.9 | 24 |
| 1990 | 17.4 | 21 |
| 1989 | 16.3 | 19 |
| 1988 | 17.2 | 13 |
| 1987 | 12.8 | 13 |
| 1986 | 12.1 | 14 |